Fire extinguisher



Patented July 14, 1942 FIRE EXTINGUISHER John W. Wright, Dayton, Ohio,assignor to The Fyr-Fytcr Company, Dayton, Ohio, at corporation of OhioNo Drawing. Application September 2, 1939,

Serial N0. 293,221

'5 Claims.

It is a further object to provide a charge for a fire extinguisher ofthe foam-generating type Y which in operation will produce quickly anduniformly a large quantity of highly effective fireextinguishing foam,resulting in extinguishing of the fire in a rapid and superior manner.

. It is a further object to provide for use in a foam-type fireextinguisher a novel foam stabilizing material which is made effectiveunder predetermined controlled conditions and 'which'proi.

vides for economically securing a highly effective long-lastingfire-extinguishing foam.

It is a further object to'provide-an extinguisher of the foam-type inwhich the foam as generated upon the operation of the extinguisher ismaintained under controlled conditions, resulting in uniformity ofoperation and superior quality of generated foam for fire-extinguishingpurposes.

It is a still further object to provide a foam charge including astabilizer material and a material for maintaining predeterminedcontrolled conditions, which charge is effective in its operation,definite and uniform in its composition, and which is practically freefrom decomposition and not subject to mold or bacterial growth or thelike, over extended periods of time in the extinguisher.

Other objects and advantages will be appar- -ent from the descriptionand the appended claims.

This application is a continuation in part of copending applicationSerial No. 159,121, filed August 14, 1937, and assigned to the sameassignee as this application.

In the fire extinguishing art certain types of extinguishers have beendeveloped for particular effectiveness in the extinguishing of fires ofdifferent characteristics, not all methods of extinguishing fires beingof the same effectiveness when applied to fires involving differentmaterials. For example, the application of water to fires involvingwood, paper, textiles and the like is highly effective, but it is oflesser value in ex-' tinguishing fires involving oils, greasesandvolatile solvents. The foam-type extinguisher produces in operation ablanket of flame-smothering and air-excluding foam, which floats on thesurface of burning fluid such as oils, greases and the like, excludingair and oxygen from the seat of the fire and resulting in effectivelysmothering such a fire.

The present invention relates to such foamtype extinguishers andprovides a foam-generating charge which is of superior effectiveness inthe extinguishing of fires. In operation, the extinguisher of thisinvention develops a foam which has superior flowing power such that itflows more readily over the surface of burning fluids, such, forexample, as oils, greases and the like, quickly forming :an effectivefiame-srnothering blanket and extinguishing the fire. This is highlyimportant in securing the maximum of fire-extinguishing effect from anextinguisher of'any predetermined .size and is of special importance inconnection with the extinguishing of fires involving flammable andvolatile liquids. In this latter case the rapidity of flow of thefireextinguishing foam over .the burning surface of the fluid and itsgreat effectiveness in quickly bringing the flame under control makes itpossible for the operator to approach the seat of fire more quickly than[in the ordinary case, so that he is enabled to approach closely to thefire where the fire-fighting equipment may be used to the bestadvantage. Thus the extinguisher of the present invention is effectiveupon fires in open vessels of turpentine, lacquer solvents, paintsolvents and like materials which are extremely difficult to extinguishwith the media heretofore available.

Foam-generating type extinguishers consist generally of a vesselprovided with a discharge opening and constructed to withstand internalpressure and adapted to contain an aqueous solution of one of thefoam-generating ingredients. Positioned within or adjacent this vesselis another vessel adapted to contain an aqueous solution of theremaining portion of the foam-generating ingredients, the positioning ofthe two vessels be ing such that these solutions are normally keptseparate when the device is in the inoperative position. The severalingredients of these two solutions are selected so that upon operation othe device to cause mixing of these solutions a chemical reactionoccurs. Thus if one of these solutions is an aqueous solution ofaluminum sul fate, for instance, and the other solution is an aqueoussolution of sodium bicarbonate, a chemi-- cal reaction will occurwhichwill result in the formation of sodium sulfate, carbon dioxide andaluminum hydroxide, the carbon dioxide being in the gaseous state, anddeveloping pressure to expel the contents of the device through thedischarge opening. Aluminum hydroxide, which is practically insoluble inaqueous solutions of this character, remains in suspension in thesolution in a finely divided state and is expelled with the solutionthrough the discharge fitting ofthe device.

Due to the fact that carbon dioxide, especially under pressure, isappreciably soluble in aqueous solutions, a substantial percentage ofthe total quantity of carbon dioxide generatedas a result of thechemical reaction is dissolved in the fluid portion of the reactionmixtureand-is discharged from the device in the discharge stream.' Andsince the interior of the device is under aprestion has in the pastattended upon the use of natural products, such as extracts of licoriceand other extracts of barks, leaves, roots and the like, as a result ofthe growth cf mold or other microorganisms in that portion of the chargecontaining such material. With the stabilizer material inaccordanceherewith, there is substan- ,tially no change in'ithe charge even overextended periods of'time, the extinguisher thus remaining in conditionsuitable for immediate operation without frequent inspections orrecharging.

.. As pointed out above the function of a stabilizer is to toughen theenvelope surrounding a sure, the dissolved gas in the discharge streamincreases in volume as it is discharged from the outlet into theatmosphere. Thus fluid from within the container is not discharged as asolid stream of fluid, but as an admixture of fluid and gas, with thegas expanding upon discharge. As

.a'result or this condition a large'number'of very small bubblesareformed', each bubble consisting of a central portion of carbondioxide gas and small bubble of gas and prevent coalescence of adjacentbubbles which result in the escape of gas and collapse of the body offoam. It is believed that-stabilizing materialsfunction by reason of themolecules of such materials orientv ing themselves or arrangingthemselves on the an outer envelope or skin of-fluid or liquid'materialfrom the" device. Dueto the insoluble aluminum hydroxide formed as 'a'result of the chemical reaction and carried insuspension in thedischarge stream,th'e outer'envelop'e or skin sisting-of the ends oflike molecules.

enclosing the center o f'each bubble is sufiiciently tough and elasticto maintain its form for an appreciable length of time'with theresult-that the stream discharged by such a device consists of a frothor foam. However'such foam unless properly controlled iscomparatively'unstable due to the tendency of adjacentbubbles tocoalesce and permit the escape of entrapped gas with the result that thevolumeoccupied by the foam decreases more rapidly than desiredforeffective fire extinguishing purposes. Y

In accordance with the present invention a foam charge is provided, suchcharge embodying surface of the envelope surrounding a bubble in such amanner that coalescence of adjacent bubbles is retarded.' Thus, forinstance, ifa stabilizingmaterial is selected of such a molecularconstruction that one end of the molecule of such material isadsorbed'by the aqueous envelope and the other end is not adsorbed, theouter surface of such a bubble will present a surface con-Whenadsorption of one portion of the molecule occurs, the remainingportion of the molecule becomes negatively charged with the result thatwhen a bubble, the outer surface of which consists of molecules havinglike ends negatively charged approaches closely a similar bubble,coalescence will be inhibited due to the mutual repulsive forces actingbetween such surfaces. Thus, coalescence of adjacent bubbles ismaterially reduced with the result that foam consisting of such bubblesis produced in greater volume and is longerlasting than foams .in which.this coalescence occurs rapidly.

The stabilizer materials of the present invention are syntheticmaterials of hydrocarbon nasuitably reactive solutions such as anA'solution, acid in reaction, and containing an aqueous solution of asalt such as aluminum sulfate, and a 13" solution, alkaline'in'reaction, and containing an aqueous solution of a salt such-assodium bicarbonate. Upon intermixture of these solutions in theoperation of the extinguisher a gentur'e select'edto .have predeterminedmolecular sizes and molecular structures such that these materials willproperly orient themselves with re- .lation tothe envelope .ofindividual bubbles so that a foam of super'ior characteristics -.isoberation of gaseous pressure takes placeproviding for the expelling ofthe fire-extinguishing liquid out of the extinguisher substantially asdescribed above.

With such charge are incorporated'ma'terials providing for maintainingcontrol of the body of generated foam so that the tendencyfo'r theformed bubbles to coalesce is controlled and re-' duced and for thispurpose-there is included a predetermined small" quantity of 'a materialcapable of developing 'stabilizingefiect upon the successfully.-

In order that a molecule may orient itself in such amanner that itfunctions efliciently as a stabilizer it must contain certain definitegroupgenerated foam. Such stabilizer material'is ofdefinite andpredetermined composition such that its effect may be controlledaccurately. A material of definite'comp'osition is utilized, preferably'a synthetic stabilizer material, with unithe electrostatic forces aresuch that adsorption formity of composition and'operating character-'istics, avoiding the use offnatural' products as practiced in the pastwhich are objectionable from lacli of uniformity, variation withdifferent sources of supply, seasons of the'year, etc. Likewise thestabilizer material of this invention is substantially inert and notsubject to deterioration nor adapted to support the growth of bacteriaor other micro-organisms.' Seriou i ings-of elements, termed polargroups, or molec-- ular structures which act as polar groups. The termfpolar groups is used herein to designate those groupings of chemicalelements in which to aqueous surfaces is caused to readily occur whilethe term non-polar? is used to designate those groupings of chemicalelements in which the electrostatic forces are such that adsorption doesnot readily occur at aqueous surfaces.

- As examples of highly polar groups may be mentioned the hydroxyl !OH),carboxyl -(-"C0.0H), vmercaptan (SH), the. halogens amino .others ofsimilar characteristics.

:dound that the points of unsaturationun the hyclrocarbon chain, such asa double or triple (-01-10), ketone nitrile (CN)-,, and

It is further bond, act like polarfgnoups} and by the redeterminedselection of carbon compound s' haying ,points of unsaturation inpredetermined arrangernents a compound equivalent in its functioning inthe present invention to one containing a polar group'is provided. Ingeneral'carbon and hydrogen-when grouped together form a nonpolar"group.-

Itis important that the molecule have substantial size. as measured interms of the number of carbon atoms in the chain',-" so-'as to bringabout adequate protective-action upon the-surface of the bubbles.'Thus', it is usually found that: the

- chain should contain four or more carbon atoms.

" Onthe other hand the compound should not .be

-' excessively large as its orientation then becomes diff cult tovcontrol and for-thatreason it is ordinarily found that for. bestresults the compound should not contain in excess of approximately 18 to20 -.c ar bo-natoms between adjacent polar groups or structures whichact as polar. groups.

, To provide points of attachment for the molecule are given above, havethe same effectiveness for the purposes of the present invention, someof these groupingsbeing more readily adsorbed than are others. For=ins'tance,'the sulplionic group,

v(-SOzOH) is-mOre readily adsorbsd or has a greater effectiveness-thandoes the hydroxyl group; (--OH). When,'therefore, an hydroxyl group isused as the polar group it should be associated with a 'lesser number ofcarbon atoms to the liquid body of the envelope of the bubble thecompound should contain one or more polar groups. In the case where.the, compound-is 'rela is preferable that the compound haveincorporated more than=a single polar-group and, pref-' erably. thatsuch plurality of polar groups be distributed over thebody of' thecompound.

'-In'- the" case of aromatic compounds having a simple ring structure asingle polar group may suffice, but it is usually desired to utilize twoor three polar groups, symmetrically positioned about the molecule;v andinthe case of more complex molecules, improved results --are obtainedthrough the use of compounds having a plurality of polar groups attachedthereto.

I tively small, thatis, contains a small number of carbon atoms, asingle polar group may suiiice;' .where an extended carbon chain isemployed it 1 As examples of compounds which have been ,found t0,,givesatisfactory results in operation,

an aliphatic chainjcoi'npound of the general formula CnH2n+2 rangingfrom approximately 4 carbon atoms to 18 carbon atoms, and havingsubstituted for an end hydrogen a polar group, such, for example, as anQH'group, forming an :1-6 carbon atoms. I

utilized of compoundshaving'even a greater than when a sulphonic groupis used as the polar group. Thus a hydrocarbon chain consisting of 4 to6 carbon atoms is sufficient for one hydroxyl group, whereas a; carbonchain of 14 to 18 carbon :atoms is desired for a-sulphonic group.Similarly 15' for a single hydroxyl group, whereas a ten-membred rin'gsuch as a naphthylene nucleus, is

a six-memberedcarbon ring is generally sufficient desired whenasulphonio'group is used as the polar group. ,When highly polar groupsare used in six-membered ring structures additional hydrocarbon groupsshould-be added to such a structure, such, for instance, as methyl,ethyl or propyl groups the number and length of such chains dependingupon the polarity of the polar group or groups'usled.

It has'been'further found that, generally, a better quality of foamresults when the stabilizer is a mixture'of' closely-related compoundsthan when a single pure compound is used. For instance, if 'analkyl'chain'consisting of 14 carbon atoms is used with a single polargroup, it will be found' -advantageous to include a substantialpercentage of similar alkyl compounds having 12 and If desired, mixtures-may be range in the number-of their "carbon atoms such as from 4 to 20carbon atoms.

Furthermore, more complex compounds, such as the arakyls and alkarals,containing both an aliphatic chain-'and-an aromatic ring may haveattached thereto suitable polar groups to form compounds which producesatisfactory results in accordance with the present invention.

If the formed bubbles of foam break in too short a period of time as aresult of the dissipation or substantial change of electrical charge onthe. outer-surface of the bubble envelope, the

alcohol, or an SOaI-I sulphonic acid group, may

of..the sulphonic acid should be used in preferrence to the sulphonicaciditself. Compounds of this nature are generally colorless, neutral,nonof aryl] cOmpound'sQ 'I'he'se materials when utilized insmall'proporti'ons, for example; inthe order of about 1.5 to 5% based]on theweight'of the'char'ge of salt vvithwhich they are used, are

found to produc e lextiiaordinary' results in foam -forn'ia'tion asabove'de's cribed. j Not allot thepolar groups, examples of which beutilized. Preferably, where a sulphonic acid. group is utilized, thesodiumor potassium salt 1 resistance of the bubbles to coalescing isdiminished and the body of foam is no longer maintained as an effectiveflame-smothering blanket.

-' It is'desired to maintain the foam for as long a time as possible andto this end it is desired to avoid such change in the charge conditionof the bubbles as would lead to-rapid coalescence. Such change mayresult from a-substantial change in hydrogen-ion concentration or pHvalue of the foam and it has been found that if the pH value of the foamdeparts substantially from a neutral condition the quality of the foamis adversely affected.

In the operation of the usual extinguisher where a quantity of Asolution is discharged into a body of B solution, or vice-versa, onlytially neutral.

chemically equivalent portions of these solutions can react and theproduct of reaction is substan- But this reaction product may havephysically present therewith a small quantity of A solution or Bsolution, depending upon which solution is in excess, with the resultthat this reaction product including the foam bubbles themselves, Whilehaving a hydrogen-ion concentration substantially neutral when formedmay have a non-neutral hydrogen-ion concentration as actuallydischarged.

In accordance with this invention it has been discovered that certainmaterials, such as the monobasic and dibasic phosphates-of sodium andpotassium, the acetates of sodium and potassium, and the borates ofsodium and potassium, when present in small quantities, materiallyaffect the performance of the stabilizer under these conditions. Thesematerials are especially desirable for incorporation in the B portion ofthe charge. It is important that the buffer materials be and remaisubstantially inert in the portion of the charge with which they areincorporated prior to Operation of the extinguisher to avoid prematurereaction thereof. As an example of buffer materials suitable for usewith the A portion of I the charge, aluminum phosphate or acetate may beutilized. It is believed that these compounds partially dissociate andresist the change in hydrogen-ion concentration causedby themechanically admixed portions of unreacted solution carried by thegenerated foam. That is, it is believed, when the hydrogen-ionconcentration of the generated foam ischanged from a substane tiallyneutral condition that these compounds partially dissociate and releaseor absorb hydrogen-ions restoring the generated foam to substantially aneutral state with the result that the negative charges carried byadsorbed stabilizer molecules become effective and thereby prevent arapid collapse of the foam with resultant improvement in its quality andeffectiveness. 'While these materials are not the only materialssuitable for this purpose, such materials are available generallycommercially, and economically, so that they form preferred materialsfor use as what will be termed herein bufiersf. effective to develop abuffering and in conjunction with the stabilizer a protective actionupon the generated foam. The quantity utilized may .be rather small,such, as in the examples given below, as of the order of about 1 to 1.5%basedon the weight of the salt portion of the charge with which they areused. I

Such buffer material may be satisfactorily added either to the Asolution or to the B solution, and either in thepresence or absence, ofthe stabilizer material. It is desired, however, particularly whereboth-stabilizer and buffer ma-- terial are present together in oneportion of the charge, that the materials be compatible with As anotherexample a B solutionmay con tain:

where. the radical may be substantially either hexadecyl containing lficarbon atoms or octa decyl containing 18' carbon-atoms.

- Still another'exampla-a .13 solution may contain:

1 Per cent- Sodium bicarbonate 10.00

' Sodium alkyl sulfate .10

Sodium tetraborate -(10 H2O) .15

WateLI; 89.75

each other, and not subject to mutual reaction prior to the actualoperation of the extinguisher.

As a specific example of a charge for afire extinguisher formed inaccordance with the present invention, an A" solution is madeupcontaining:

where the alkyl radical is substantially octyl and contains 8 carbonatoms. Throughout these examples the two solutions are to be mixed inthe general proportion of 14 parts of the A solutiorr to 66 parts of theB solution.

Per cent Aluminum sulfate 46.5 Aluminum phosphate .6 Water 52.9

and B solution:

I Per cent Sodium bicarbonate 10.00

. Sodium alkyl sulfate .12 'Water 89.88

where the alkyl radical may :be an unsaturated carbon chain such ashexadenyl or octadenyl containing 16 or 18' carbon atoms respectively.

Still another example, a B solution may contain:

' Per cent The following is an example of the buffer being present intheA solution:

The examples given above-are suitable for the generation of foam whenusecl 'in extinguishers of standard design of a capacity of 2 gallons.Suitable change in the proportions given above may be made toseoure themost desirable operating results in extinguishers of a capacity otherthan approximately 2% gallonsor other than of usual design.

While the proportions given above have been found to be most suitablefor these particular compounds when used in one-kind of extinguisher, itmust be pointed out that changes in extinguisher design or sizemay-require proportions different from those set out above. Further,these examples are of stabilizers having 8, 12, 16 and 18 carbon atomsin the chain, and if the chain length is decreased, it has been foundthat'the quantity of stabilizer used should be increased,

, not in direct proportion to the decrease in chain length, but ininverse exponential relation thereto. Similarly, if the chain lengthis'increased, the quantity of stabilizer required may be decreased inexponential proportion.

The quantity of buffer material required for generation of maximum foamvolume varies with the kind and amount of stabilizer used. If a largerquantity of stabilizer is necessary, the quantity of buffer. materialused should be increased accordingly; while if a smaller quantity ofstabilizer is required, a correspondingly smaller quantity of buffermaterial may be used.

In the examples given above, the quantity of buffer material specifiedis such that the maximum foam volume is secured with these particularstabilizers, and if other stabilizers are used, the quantity of bufiermaterial may be increased or decreased in accordance with therelationships set out above for maximum eifectiveness.

The extinguisher of this invention comprises a charge which in operationprovides for securing extraordinary results in effectiveness inextinguishing fires. The charge includes a stabilizer material ofpredetermined definite characteristics and in predetermined quantitybased upon such known characteristics. Such material is incorporated.with either the A" solution or the B solution as determined to be mostsatisfactory, and is substantially neutral and inert, and may also becolorless, odorless, non-corrosive and nontoxic. The charge alsoincorporates a buffer material therein which exerts its effectivenessduringoperation to provide a foam having the desired hydrogen-ionconcentration such that the entire body of the foam will have thosecharacteristics best adapting it to the furtherance of its smotheringand flame-extinguishing action.

While the process and composition of matter herein described constitutespreferred embodiments of the invention, it is to be understood that theinvention is not limited to this precise process and compositionofmatter, and that changes may be made therein without departing from thescope of the invention which is defined in the appended claims.

What is claimed is:

1. A foam charge for a fire extinguisher of the foam generating typecomprising chemically reactive foam forming materials including aluminumsulfate having an acid reaction and a material having an alkalinereaction adapted to be brought together with said acid material in thepresence of water to develop carbon dioxid gas andto form a fireextinguishing foam, a foam stabilizer, and a buffer material present inand compatible with one portion of said charge in an amount of the orderof 1% to 1 /2% of the salt portion of the charge with which it ispresent, said material being selected from the group consisting ofsodium, potassium and aluminum phosphates, acetates and borates.

2. The foam charge as defined in claim 1 in which said foam stabilizercomprises a hydrocarbon material having a polar group attached thereto.

3. The foam charge as defined in claim 1 in which said foam stabilizercomprises an aliphatic hydrocarbon material having from 4 to 20 carbonatoms in the molecule and also having a polar group attached thereto.

4. The foam charge as defined in claim 1 in which said foam stabilizercomprises an aryl compound having a polar group attached thereto. 5. Thefoam charge as defined in claim 1 in which said foam stabilizercomprises compounds containing an aliphatic chain and an aromatic ringhaving polar groups attached thereto.

JOHN W. WRIGHT.

